TECHNET Archives

May 2014

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Steve Gregory <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steve Gregory <[log in to unmask]>
Date:
Tue, 20 May 2014 08:06:55 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (139 lines)
Hi Carmen!

Finally got your photos! I have them posted now. They are here:

http://stevezeva.homestead.com/1.jpg

http://stevezeva.homestead.com/7.jpg

So, is this happening on multiple boards? The same location on all
boards? This looks pretty serious, I wouldn't trust the boards.
Definitely need a cross-section at a minimum to see what is going on...

Steve 


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carmen Aloisi
Sent: Monday, May 19, 2014 7:17 AM
To: [log in to unmask]
Subject: [TN] Rif: RE: [TN] Rif: Re: [TN] pcb issue led to smt
components drop from pcb

Hi Steve
here they are, these are the only kind of components that dop the other
ones are well fixed on the pcba.
Thanks a lot,

Carmen



Hi Carmen!

Just reply to this email and I'll post your pictures....

Steve


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carmen Aloisi
Sent: Monday, May 19, 2014 12:58 AM
To: [log in to unmask]
Subject: [TN] Rif: Re: [TN] pcb issue led to smt components drop from
pcb

Dear all
thanks a lot for your promt reply and suggestions, the pcbs have leaded
hasl surface finishing I agree with you about potential intermetallic
issues... fail pcbas are travelling right now from customer to our plant
here in Italy and then I'll make some cross section.

I'd like to share pictures, how shall I contact mr Steve Gregory in
order to post them?

Have a nice day
Carmen

Carmen Aloisi
Quality Manager

Eutron S.p.A.
Via Crespi 29 24020 Pradalunga (BG) Italy ph. +39 035697011 fax +39
035697090 m. +39 3355666074 www.eutron.com p.i. 01805190160




Hi Carmen-

You must get the surface analyzed.  I believe that it "looks like" bare
exposed copper, but the odds are highly against that.  As Vladimir has
suggested, you can hire an expert to do the whole analysis.  Or you can
try to make this an educational journey for yourself.  If you get the
surface analyzed, you'll need an analytical technique capable of
identifying the various species and thicknesses of intermetallics which
are on the metal surfaces.

Also, you need to understand the usage environment.  I believe that with
the appropriate amount of temperature cycling, you can get the
components to fall off of anything, provided there is a temperature or
temperature coefficient of expansion difference between the component
and substrate.

Looks like I might be the first to set off some tirades by mentioning
"black pad".  This is a very ugly intermetallic which is associated with
ENIG surface finish, and we providers of electronic assemblies spend
many sleepless nights about it because you can have a beautiful joint
which fails in even fairly mild usage environments.  Obviously we don't
have enough information to suggest this as your problem, but it fits the
final result (as do many other things!).

Shock will take off SMT components also, but that's usually a negligible
probability (exceptions include crystals separating from cell phone
motherboards when the cell phones are dropped or thrown).

Can you provide pictures?  We like to see pictures in TechNet.  You
can't broadcast them directly, and we were using some kind of sharing
site, but this guy named Steve Gregory takes pride in making it easy to
send him pictures and he'll post them.  I think the "cc" address in this
email is his current one, but he's changed companies a few times, so I'm
not positive.
He seems to always watch for opportunities to help like this.

Once you post shots, all of the TechNet experts will come out of the
woodwork with additional questions and arguments guaranteed to be
somewhat amusing and possibly very educational.

Wayne Thayer

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carmen Aloisi
Sent: Friday, May 16, 2014 11:48 AM
To: [log in to unmask]
Subject: [TN] pcb issue led to smt components drop from pcb

Hello
I'm new to this forum and I'd like to address the following issue to the
group:
after 3 years from delivery of a batct of pcbas we got back from
customer some of them  where components are dropping from the pcbas, the
solder remains on the component pin and the pads are with exposed
copper.
Could you help me in understanding what was wrong on pcb supplier
process or on ours?

Thanks a lot in advance
Carmen Aloisi
Quality Manager

Eutron S.p.A.
Via Crespi 29 24020 Pradalunga (BG) Italy ph. +39 035697011 fax +39
035697090 m. +39 3355666074 www.eutron.com p.i. 01805190160


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

ATOM RSS1 RSS2